Polarization offset of homogeneous Bi3.15Nd0.85Ti3O12 ferroelectric thin films

In this report, the polarization offset usually observed in compositionally graded ferroelectric thin films was observed in homogeneous Bi3.15Nd0.85Ti3O12 thin films sandwiched in Pt electrodes. The observed polarization offset was studied as functions of temperature and of the driving voltage amplitude using a modified Sawyer-Tower circuit. The polarization offset is obvious only at temperatures above 150 degrees C and increases with increasing testing temperature and amplitude of driving voltage. The reported phenomena demonstrate that the composition gradient is not a necessity for such a polarization offset. The strong temperature and voltage dependence indicates that the polarization offsets may be related to thermionic charge injection, which is asymmetric to top and bottom electrodes. (c) 2008 American Institute of Physics. [DOI: 10.1063/1.2999534]